Eye and/or gaze position tracking systems have many beneficial uses. For example, gaze position tracking systems may help disabled persons with cursor position control when using computer systems. Gaze position tracking may also find use in computer gaming, military applications, as well as assisting web-based advertisers in gauging advertising placement effectiveness.
In order to determine gaze direction, most if not all commercially available eye and/or gaze position tracking systems rely on reflections from the various portions of the eye, called Purkinje reflections, to track gaze direction. Purkinje reflections are not only small relative to the size of eye, but are also very faint, and thus systems based on Purkinje reflections use a high resolution digital camera directed toward the eye in order to discern the Purkinje reflections from other more prominent features. As a further difficulty, Purkinje reflections are affected by head position, and thus systems that rely on Purkinje reflections may require the user's head be held still or utilize additional systems (e.g., another camera) to compensate for head movement. Based at least on the hardware required to implement such systems, the cost of most commercially available systems is prohibitive for the great majority of prospective users.
Moreover, commercially available gaze position tracking systems in many cases require large text and icon sizes to compensate for lack of fine cursor position control. Thus, such commercially available systems may not be directly compatible with off-the-shelf portable and desktop computer systems.